from selenium import webdriver
from selenium.webdriver.common.by import By

driver = webdriver.Firefox()
driver.get("https://mail.qq.com/")
driver.implicitly_wait(30)
# 切换到子页面
# frameEl = driver.switch_to.frame(By.ID,'ptlogin_iframe')
driver.switch_to.frame("ptlogin_iframe")
driver.find_element(By.LINK_TEXT, '密码登录').click()
